Saturday, January 26, 2008

I've noticed something and that's really bad ... *sigh*

My favourite filter design becomes unstable when quickly changing from greater to lower cutoff frequencies and explodes. The beta version already had a safety condition which resets the filter when it's going to explode (you'll hear a sharp click noise).
After tinking about this for a while I came up with some different kinds of fixes:

1. Limit the minimum FC. But this limit prevents the filter from running nearly closed, so this is not the perfect solution.

2. Always interpolate FC inside the filter. This should prevent the filter from exploding but would also cause some more CPU load. I can't say how much this will be, but I'll check this.

3. Smart interpolation of FC. This means: checking for rapid FC changes towards zero and only interpolating in this cases ... but this would cause massive pops in CPU usage when 'going down'.

4. Exchange the filter. <-- never ever.

Well, it's late at night, I have to go to bed but I will think about this and try some solutions tomorrow.

Stay tuned ...


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